SIGNAL PROCESSING DEVICE FOR READER TARGETED TO CODES SIGNAL PROCESSING METHOD AND SIGNAL PROCESSING PROGRAM

Provided is a signal processing device intended to improve failure to read a barcode due to a defect of the barcode to the manner of swiping the barcode by the sensor or the like. The device is provided with: a variable amp for outputting an output signal that is a signal corresponding to an input signal it being possible to adjust the offset and gain of the variable amp; a comparison means for comparing the level of the output signal to a plurality of threshold values; a detection means for detecting on the basis of the result of comparison by the comparison means deviation of the offset of the variable amp excess or deficient gain of the variable amp or both; and adjustment means for adjusting the offset the gain or both of the variable amp on the basis of the result detected by the detection means.